Is Object Space Normals the same as Bent Normals
No its not the same, this is object and tangent normals are related to the direction of the face at 'that' point. One is aligned to the world (object) and the other is aligned to the axis of the mesh (tangent).

Bent normals are as stated (after some research) the average of the unoccluded directions, causing a curve/lip/bend as they rotate.

Further information on what a bent normal map is; https://docs.unrealengine.com/en-us/Engine/Rendering/LightingAndShadows/BentNormalMaps